[bena]

Basically, you want both lanes to effectively spread out to where those in one could be placed in the other without overlapping vehicles.

The goal is to have both lanes move slowly, but constantly. To basically have a "1 and 1" progression through the chokepoint: 1 from the left, 1 from the right.

It is a rough balance because you have those who don't want to let others merge at all. And there are those who want to merge at all costs. Both of which violate the "1 and 1" guideline which gives everyone at least the illusion of progress.